The invention relates to indenyl compounds that can be used as catalyst component for the polymerisation of olefins. The invention also relates to a process for the polymerisation of olefins, using indenyl compounds. Such indenyl compounds are for instance known from WO-A-94/11406.
In said patent publication indenyl compounds are described of formula 
wherein:
M is a transition metal from the lanthanides or from group 3, 4, 5 or 6 of the Periodic System of Elements,
Q is an anionic ligand to M,
k is the number of Q-groups and equals the valence of M minus 2, and
R is a bridging group. It is now surprisingly discovered that indenyl compounds, wherein R contains at least one sp2-hybridised carbon atom that is bonded to the indenyl group at the 2-position, are more active and/or give polymers with a higher molecular weight (Mw) and/or yield a polypropylene with a low amount of misinsertions when used as a catalyst component during the polymerisation of olefins.
The indenyl compounds according to the invention are indenyl compounds according to (1) 
wherein:
M is a transition metal from the lanthanides or from group 3, 4, 5 or 6 of the Periodic System of Elements,
Q is an anionic ligand to M,
k is the number of Q groups, and equals the valence of M minus 2,
R is a bridging group containing at least one sp2-hybridised carbon atom that is bonded to the indenyl group at the 2-position,
and Z and X are substituents, with the exclusion of Ti(deshydronorbiphenacene)dichloride. In xe2x80x98Synthesis, Structure, and Properties of Chiral Titanium and Zirconium Complexes Bearing Biaryl Strapped Substituted Cyclopentadienyl Ligandsxe2x80x99, W. W. Ellis c.s., Organometallics 1993, 12, 4391-4401 Ti(deshydronorbiphenacene)dichloride is described, but not the polymerisation of olefins with this indenyl compound.
The various components of the indenyl compound of the present invention will hereafter be discussed in more detail.
a) The Transition Metal M
The transition metal M is selected from the lanthanides or from group 3, 4, 5 or 6 of the Periodic System of Elements. The Periodic System of Elements is understood to be the new IUPAC version as printed on the inside cover of the Handbook of Chemistry and Physics, 70th edition, CRC Press, 1989-1990. The transition metal M is preferably chosen from the group Ti, Zr, Hf, V and Sm. Most preferably the transition metal M is Ti, Zr or Hf.
b) The Anionic Ligand Q
The Q group in the indenyl compounds according to the invention comprises one or more uni- or polyvalent anionic ligands to the transition metal M. As examples of such ligands, which may be the same or different, the following can be mentioned:
a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a group with a heteroatom chosen from group 14, 15 or 16 of the Periodic System of Elements, such as:
an amine group or amide group,
a sulfur-containing compound, such as sulphide and sulphite,
a phosphorus-containing compound, such as phosphine and phosphite.
The ligand Q can also be a monoanionic ligand bonded to the transition metal M via a covalent metal-carbon bond and which is additionally capable to non-covalently interact with M via one or more functional groups. The functional group mentioned above can be one atom, but also a group of atoms connected together. The functional group is preferably an atom of group 17 of the Periodic Table of the Elements or a group containing one or more elements from groups 15, 16 or 17 of the Periodic Table of the Elements. Examples of functional groups are F, Cl, Br, dialkylamino and alkoxy groups. Q can for instance be a phenyl group in which at least one of the ortho-positions is substituted with a functional group capable of donating electron density to the transition metal M. Q can also be a methyl group in which one or more of the alpha-positions is substituted with a functional group capable of donating electron density to the transition metal M. Examples of methyl groups substituted in one or more of the alpha-positions are benzyl, diphenylmethyl, ethyl, propyl and butyl substituted with a functional group capable of donating electron density to the transition metal M. Preferably at least one of the ortho-positions of a benzyl-group is substituted with a functional group capable of donating electron density to the transition metal M.
Examples of these Q groups are: 2,6-difluorophenyl, 2,4,6-trifluorophenyl, pentafluorophenyl, 2-alkoxyphenyl, 2,6-dialkoxyphenyl, 2,4,6-tri(trifluoromethyl)phenyl, 2,6-di(trifluoromethyl)phenyl, 2-trifluoromethylphenyl, 2-(dialkylamino)benzyl and 2,6-(dialkylamino)phenyl. The man skilled in the art can determine the suitability of these and other ligands through simple experimenting.
The number of Q groups in the indenyl compound according to the invention (index k in formula (1)) is determined by the valence of the transition metal M and the valence of the Q groups itself. In the indenyl compounds according to the invention k is equal to the valence of M minus 2 divided by the valence of Q.
Preferably, Q is a mono-anionic ligand. Most preferably, Q is Cl or a methyl group.
c) The Bridging Group R
R is a bridging group containing at least one sp2-hybridised carbon atom that is bonded to the indenyl group at the 2-position. In general and in this description, the substituent locants of the indenyl ring are numbered in accordance with the IUPAC Nomenclature of Organic Chemistry, 1979, rule A 21.1. The numbering of the substituents for indene is given below. This numbering is analogous in the case of an indenyl ligand: 
The R group connects the indenyl group with the cyclopentadienyl group in the indenyl compound according to the invention. Sp2-hybridised carbon atoms are also known as trigonal carbon atoms. The chemistry related to sp2-hybridised carbon atoms is for instance descibed by S.N. Ege, Organic Chemistry, D.C. Heath and Co., 1984, p. 51-54. Sp2-hybridised carbon atoms are carbon atoms that are connected to three other atoms. In the indenyl compounds according to the invention the sp2-hybridised carbon atom is in any case connected to the indenyl group at the 2-position.
The sp2-hybridised carbon atom may be a part of, for instance, an alkylene-containing bridging group R or of an aryl group forming part of the bridging group R.
Alkylene-containing bridging groups can be, for instance of the formulas 
wherein Rxe2x80x2 is a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an aralkyl group, an alkoxy group, an aryloxy group, a group with a heteroatom chosen from group 14, 15 or 16 of the Periodic System of Elements, such as
an amine group or amide group,
a sulfur-containing compound, such as sulphide and sulphite,
a phosphorus-containing compound, such as phosphine and phosphite, E can be carbon, silica or germanium atom and
s is 1-20.
Examples of alkylene-containing bridging groups are ethylene, propylene, which can also be subsituted.
Examples of aryl groups that can form part of a bridging group are phenylene, biphenylene, pyridyl, furyl, thiophyl and N-substituted pyrroles, such as N-phenylpyrrole or an inorganic compound containing an aromatic group, for instance a metallocene compound and a ferrocene compound.
The bridging group R preferably contains at least one aryl group; preferably the aryl group is a phenylene group. When R is a phenylene group the indenyl compounds are more active catalyst components. More preferably R is a bisaryl group; preferably a 2,2xe2x80x2-biphenylene. When R is a 2,2xe2x80x2-biphenylene group the indenyl compound, as a catalyst component, gives rise to better comonomer incorporation, polymers with a higher molecular weight and to a propylene homopolymer with a higher isotacticity when propylene is polymerised.
d) The Substituents X1-X4 
The cyclopentadienyl group may be substituted. The substituents X may each separately be hydrogen or a hydrocarbon radical with 1-20 carbon atoms (e.g. alkyl, aryl, aryl alkyl). Examples of alkyl groups are methyl, ethyl, propyl, butyl, hexyl and decyl. Examples of aryl groups are phenyl, mesityl, tolyl and cumenyl, Examples of aryl alkyl groups are benzyl, pentamethylbenzyl, xylyl, styryl and trityl. Examples of other substituents are halides, such as chloride, bromide, fluoride and iodide, methoxy, ethoxy and phenoxy. Also, two adjacent hydrocarbon radicals may be connected with each other in a ring system. In this way an indenyl can be formed by connection of X1 and X2, X2 and X3, X3 and X4, or fluorenyl can be formed by connection of both X1 and X2 and X3 and X4.
X may also be a substituent which instead of or in addition to carbon and/or hydrogen may comprise one or more heteroatoms from group 14, 15 or 16 of the Periodic System of Elements. Examples of such a heteroatom containing substituents are: alkylsulphides (like MeS-, PhS-, n-butyl-S-), amines (like Me2N-, n-butyl-N-), Si or B containing groups (like Me3Si- or Et2B-) or P-containing groups (like Me2P- or Ph2P-).
e) The Substituents Z1-Z6 
The indenyl group may be substituted. The substituents Z may each separately be a substituent as described under d for X. Two adjacent hydrocarbon radicals may be connected with each other in a ring system. The Z1 and Z2 substituents can together with the X1 and X4 substituents form a second bridge that connects the indenyl group with the cyclopentadienyl group in the indenyl compound according to the invention. The second bridge can be a bridge as described under c, but can also be a bridge having the following structure:
(xe2x80x94ER32xe2x80x94)p
where p=1-4 and E is an element from group 14 of the Periodic System. R3 can be the same substituent as described for X under d.
Preferably, because these indenyl compounds are the most active ones, the indenyl compound has the structure of formula (2) 
wherein:
M is a transition metal from the lanthanides or from group 3, 4, 5 or 6 of the Periodic System of Elements,
Q is an anionic ligand to M,
k is the number of Q groups, and equals the valence of M minus 2,
R is a bridging group containing at least one sp2-hybridised carbon atom that is bonded to one of the indenyl groups at the 2-position,
and Z and X are substituents as defined herein before.
The invention is also directed to ligand presursors that can be used to prepare the indenyl compounds according to the invention. The ligand precursors have a structure according to formula (3) 
wherein:
R is a bridging group containing at least one sp2-hybridised carbon atom that is bonded to the indene group at the 2-position
and Z and X are substituents as defined here before, 20 with the exclusion of
2,2xe2x80x2-bis(2-1H-indenyl)-6,6xe2x80x2-dimethyl-1,1xe2x80x2-biphenyl,
2,2xe2x80x2-bis(2-1H-indenyl)-1,1xe2x80x2-biphenyl and
2,2xe2x80x2-bis(2-1H-indenyl)-1,1xe2x80x2-binaphthalene.
The meaning of the various components is further described hereabove.
In xe2x80x98Synthesis, Structure, and Properties of Chiral Titanium and Zirconium Complexes Bearing Biaryl Strapped Substituted Cyclopentadienyl Ligandsxe2x80x99, W. W. Ellis c.s., Organometallics 1993, 12, 4391-4401 the ligand precursors 2,2xe2x80x2-bis(2-1H-indenyl)-6,6xe2x80x2-dimethyl-1,1xe2x80x2-biphenyl, 2,2xe2x80x2-bis(2-1H-indenyl)-1,1xe2x80x2-biphenyl and 2,2xe2x80x2-bis(2-1H-indenyl)-1,1xe2x80x2-binaphthalene are mentioned. In this article the use of indenyl compounds according to the invention for the polymerisation of olefins is not described and the advantages of the indenyl compounds according to the invention are not suggested.
Preferably the ligand precursors have a structure according to formula (4) 
wherein:
R is a bridging group containing at least one sp2-hybridised carbon atom that is bonded to one of the indene groups at the 2-position
and Z and X are substituents as defined herein before with the exclusion of
2,2xe2x80x2-bis(2-1H-indenyl)-6,6xe2x80x2-dimethyl-1,1xe2x80x2-biphenyl,
2,2xe2x80x2-bis(2-1H-indenyl)-1,1xe2x80x2-biphenyl and
2,2xe2x80x2-bis(2-1H-indenyl)-1,1xe2x80x2-binaphthalene. More preferably the bridge R contains at least one phenylene group. Most preferably the bridge R is a 2,2xe2x80x2-biphenylene with the exclusion of a ligand with the structure 2,2xe2x80x2-bis(2-1H-indenyl)-1,1xe2x80x2-biphenyl.
The invention further relates to a process for the preparation of ligand precursors of formula (3) by a cross-coupling reaction of two 2-indenyl precursors of formula (5) with a bridging precursor R(Y2)2
wherein:
X1 to X8: are substituents,
Y1 and Y2 are either a leaving group or a metal containing group,
R is a bridging group,
comprising the steps of reacting 2 equivalents of the 2-indenyl precursors with 1 equivalent of the bridging precursor, Y2 being a leaving group in the case that Y3 is a metal containing group and Y2 being a metal containing group in the case that Y1 is a leaving group. The bridging group R and the X substituents are defined as herein before.
The invention also relates to a process for the preparation of a ligand precursor of formula (4) by a cross-coupling reaction of one 2-indenyl precursor of formula (5) with one cyclopentadienyl precursor of formula (6) with a bridging precursor R (Y2)2: 
wherein:
X1 to X8: are substituents,
Y1 and Y2are either a leaving group or a metal containing group,
R is a bridging group, comprising the step of reacting 1 equivalent of the 2-indenyl precursor and 1 equivalent of the cyclopentadienyl precursor with 1 equivalent of the bridging precursor, Y2 being a leaving group in the case that Y1 is a metal containing group and Y2 being a metal containing group in the case that Y1 is a leaving group. The bridging group R and the X substituents are defined as herein before. A cross-coupling reaction is a reaction of an organometallic reagent with an organic compound substituted with a leaving group. In such reaction, the carbon-atom containing the organometallic group and the carbon atom containing the leaving group are coupled through Cxe2x80x94C bond formation. Examples of leaving groups (denoted as Y above) are: halogens, diazonium groups, sulphonates, phosphates, phosphites,sulphides, sulphoxides, sulphones, selenides, carboxylates, ethers, silicon ethers, germanium ethers. An organometallic group is a group with formula
xe2x80x94Mm(Q1)n.
Wherein:
M: is an element of group 1-14 of the Periodic Table, except hydrogen and carbon
m: is the valence of M.
Q1: is a substituent of M, for example halogen, hydroxy, alkyl, alkenyl, aryl, alkoxy, alkenoxy, aryloxy, trialkylsilyloxy, trialkenylsilyloxy, triarylsilyloxy, alkylsulphide, alkenylsulphides, arylsulphides, dialkylamides, dialkenylamides, diarylamides, alkylalkenylamides, alkylarylamides, alkenylarylamides. 2 or more substituents Q1 can be connected to form a ring structure.
n is the number of substituents Q1 on M.
The organometallic group can be neutral when n=mxe2x88x921, or anionic, when n=m. In a preferred embodiment one of the leaving groups Y1 or Y2 is boronic acid. In that case the ligand . . . the ligand precursors according to the invention (according to formula 3) is by reacting 1 equivalent of an indenyl-2-boronic acid and 1 equivalent of a boronic acid substituted cyclopentadienyl containing compound with 1 equivalent of R(Y2)2, or by reacting 1 equivalent of an indenyl-2-Y1 and 1 equivalent of a cyclopentadienyl containing compound substituted with an Y1-group with 1 equivalent of R-(boronic acid)2, wherein Y1 is a leaving group and R is a bridging group.
In this process the boronic acid substituted cyclopentadienyl containing compound preferably is an indenyl-2-boronic acid or the cyclopentadienyl containing compound substituted with an Y-group is an indenyl-2-Y. The leaving group in this case Y2 can be halogen or a sulphonate. The leaving group preferably is bromine. Instead of a boronic acid also derivatives thereof, for example esters, can be used. The method described in the state of the art, for instance in WO-A-94/11406, for the preparation of the ligand precursors using a 2-indanone has the disadvantage that the yield of ligand precursor is low. Further disadvantages are that 2-indanones are expensive and that a lot of ligand precursors can not be prepared by using this method.
To prepare the ligand precursors according to formula (4) in the preferred embodiment, 2 equivalents of an indenyl-2-boronic acid are reacted with 1 equivalent of R(Y2)2 or 2 equivalents of indenyl-2-Y1 are reacted with 1 equivalent of R(boronic acid)2.
The indenyl-2-boronic acid and the boronic acid substituted cyclopentadienyl containing compound are prepared by contacting of an indene substituted with a halogen on the 2-position or an cyclopentadiene containing compound, substituted with a halogen with magnesium to form a Grignard solution which reacts with a trialkoxyborane.
Examples of trialkoxyboranes are trimethoxyborane, triethoxyborane, tributoxyborane and triisopropoxyborane.
The indenyl compounds according to the invention can be prepared via different synthesis routes, consisting of synthesis steps known as such. They can for example be prepared by converting a ligand precursor into its dianion. Compounds that are suitable for converting the ligand precursor into the dianion are organometallic compounds, amines, metal hydrides and alkaline or alkaline earth metals. Organolithium, organomagnesium and organosodium compounds can for example be used for this purpose, but also sodium or potassium. In particular organolithium compounds are highly suitable, preferably methyl-lithium or n-butyl-lithium.
The dianion thus prepared is subsequently converted into the indenyl compound of the invention by trans-metalation with a compound of a transition metal from groups 3, 4, 5 or 6 of the Periodic System of Elements (M in formula (1)). See for example EP-A-420,436, EP-A-427,697. The process described in NL-A-91,011,502 is particularly suitable. Examples of transition metal compounds that are suitable for trans-metalation are TiCl4, ZrCl4, HfCl4, Zr(OBu)4 and Zr(OBu)2Cl2. The trans-metalation is preferably carried out as in NL-A-91,011,502, in a solvent or in a combination of solvents that weakly coordinate to transition metals from the groups 3, 4, 5 or 6 with at most 1 mole equivalent, relative to the transition metal compound started from, of a Lewis base of which the conjugated acid has a pKa greater than xe2x88x922.5. Examples of suitable solvents/dispersants (pKa of conjugated acidxe2x89xa6xe2x88x922.5) are ethoxyethane, dimethoxyethane, isopropoxyisopropane, n-propoxy-n-propane, methoxybenzene, methoxymethane, n-butoxy-n-butane, ethoxy-n-butane and dioxane. Part of the reaction medium may consist of hydrocarbons (hexane and the like).
The indenyl compounds according to the invention can be used, optionally in the presence of a cocatalyst, for the polymerisation of one or more olefins.
For example, the cocatalyst can be an organometallic compound. The metal of the organometallic compound can be selected from group 1, 2, 12 or 13 of the Periodic Table of Elements. Suitable metals include, for example and without limitation, sodium, lithium, zinc, magnesium, and aluminium, with aluminium being preferred. At least one hydrocarbon radical is bonded directly to the metal to provide a carbon-metal bond. The hydrocarbon group used in such compounds preferably contains 1-30, more preferably 1-10 carbon atoms. Examples of suitable compounds include, without limitation, amyl sodium, butyl lithium, diethyl zinc, butyl magnesium chloride, and dibutyl magnesium. Preference is given to organoaluminium compounds, including, for example and without limitation, the following: trialkyl aluminium compounds, such as triethyl aluminium and tri-isobutyl aluminium; alkyl aluminium hydrides, such as di-isobutyl aluminium hydride; alkylalkoxy organoaluminium compounds; and halogen-containing organoaluminium compounds, such as diethyl aluminium chloride, diisobutyl aluminium chloride, and ethyl aluminium sesquichloride. Preferably, aluminoxanes are selected as the organoaluminium compound.
The aluminoxanes can also be aluminoxanes containing a low amount of trialkylaluminium; preferably 0.5 to 15 mol % trialkylaluminium. In this case the amount of trialkylaluminium is more preferably 1-12 mol % trialkylaluminium.
In addition or as an alternative to the organometallic compounds as the cocatalyst, the catalyst composition of the present invention can include a compound which contains or yields in a reaction with the transition metal complex of the present invention a non-coordinating or poorly coordinating anion. Such compounds have been described for instance in EP-A-426,637, the complete disclosure of which is incorporated herein by reference. Such an anion is bonded sufficiently unstably such that it is replaced by an unsaturated monomer during the co-polymerisation. Such compounds are also mentioned in EP-A-277,003 and EP-A-277,004, the complete disclosures of which are incorporated herein by reference. Such a compound preferably contains a triaryl borane or a tetraaryl borate or an aluminium or silicon equivalent thereof. Examples of suitable cocatalyst compounds include, without limitation, the following:
dimethyl anilinium tetrakis (pentafluorophenyl) borate [C6H5N(CH3)2H]+ [B (C6F5)4]xe2x88x92;
dimethyl anilinium bis (7,8-dicarbaundecaborate)-cobaltate (III);
tri(n-butyl)ammonium tetraphenyl borate;
triphenylcarbenium tetrakis (pentafluorophenyl) borate;
dimethylanilinium tetraphenyl borate;
tris(pentafluorophenyl) borane; and
tetrakis(pentafluorophenyl) borate.
As described for instance in EP-A-500,944, the complete disclosure of which is incorporated herein by reference, the reaction product of a halogenated transition metal complex and an organometallic compound, such as for instance triethyl aluminium (TEA), can also be used.
The molar ratio of the cocatalyst relative to the transition metal complex, in case an organometallic compound is selected as the cocatalyst, usually is in a range of from about 1:1 to about 10,000:1, and preferably is in a range of from about 1:1 to about 2,500:1. If a compound containing or yielding a non-coordinating or poorly coordinating anion is selected as cocatalyst, the molar ratio usually is in a range of from about 1:100 to about 1,000:1, and preferably is in a range of from about 1:2 to about 250:1.
As a person skilled in the art would be aware, the transition metal complex as well as the cocatalyst can be present in the catalyst composition as a single component or as a mixture of several components. For instance, a mixture may be desired where there is a need to influence the molecular properties of the polymer, such as molecular weight and in particular molecular weight distribution.
The indenyl compound according to the invention can be used by a method known as such as a catalyst component for the polymerisation of an olefin.
The invention relates in particular to a process for the polymerisation of (an) xcex1-olefin(s). The xcex1-olefin(s) is/are preferably chosen from the group comprising ethylene, propylene, butene, pentene, hexene heptene and octene, while mixtures can also be used. More preferably, ethylene and/or propylene is/are used as xcex1-olefin. The use of such olefins leads to the formation of crystalline polyethylene homopolymers and copolymers of both low and high density (HDPE, LDPE, LLDPE, etc.), and polypropylene homopolymers and copolymers (PP and EMPP). The monomers needed fur such products and the processes to be used are known to the skilled in the art.
The process according to the invention is also suitable for the preparation of amorphous or rubbery copolymers based on ethylene and another xcex1-olefin. Propylene is preferably used as the other xcex1-olefin, so that EPM rubber is formed. It is also possible to use a diene besides ethylene and the other xcex1-olefin, so that a so-called EADM rubber is formed, in particular EPDM (ethylene propylene diene rubber).
The catalyst composition according to the invention can be used supported as well as non-supported. The supported catalysts are used mainly in gas phase and slurry processes. The carrier used may be any carrier known as carrier material for catalysts, for instance silica, alumina or MgCl2.
Preferably, the carrier material is silica.
Polymerisation of the olefin can be effected in a known manner, in the gas phase as well as in a liquid reaction medium. In the latter case, both solution and suspension polymerisation are suitable, while the quantity of transition metal to be used generally is such that its concentration in the dispersion agent amounts to 10xe2x88x928-10xe2x88x924 mol/l, preferably 10xe2x88x927-10xe2x88x923 mol/l.
The process according to the invention will hereafter be elucidated with reference to a polyethylene preparation known per se, which is representative of the olefin polymerisations meant here. For the preparation of other polymers on the basis of an olefin the reader is expressly referred to the multitude of publications on this subject.
The preparation of polyethylene relates to a process for homopolymerisation or copolymerisation of ethylene with one or more xcex1-olefins having 3-12 carbon atoms and optionally one or more non-conjugated dienes. The a-olefins that are suitable in particular are propylene, butene, hexene and octene. Suitable dienes are for instance 1,7-octadiene and 1,9-decadiene. It has been found that the catalyst composition of the present invention is especially suitable for solution or suspension polymerisation of ethylene.
Any liquid that is inert relative to the catalyst system can be used as dispersion agent in the polymerisation. One or more saturated, straight or branched aliphatic hydrocarbons, such as butanes, pentanes, hexanes, heptanes, pentamethyl heptane or mineral oil fractions such as light or regular petrol, naphtha, kerosine or gas oil are suitable for that purpose. Aromatic hydrocarbons, for instance benzene and toluene, can be used, but because of their cost as well as on account of safety considerations, it will be preferred not to use such solvents for production on a technical scale. In polymerisation processes on a technical scale, it is preferred therefore to use as solvent the low-priced aliphatic hydrocarbons or mixtures thereof, as marketed by the petrochemical industry. If an aliphatic hydrocarbon is used as solvent, the solvent may yet contain minor quantities of aromatic hydrocarbon, for instance toluene. Thus, if for instance methyl aluminoxane (MAO) is used as cocatalyst, toluene can be used as solvent in order to supply the MAO in dissolved form to the polymerisation reactor. Drying or purification is desirable if such solvents are used; this can be done without problems by the average person skilled in the art.
Such a solution polymerisation is preferably carried out at temperatures between 150xc2x0 C. and 250xc2x0 C.; in general, a suspension polymerisation takes place at lower temperatures, preferably below 100xc2x0 C.
The polymer solution resulting from the polymerisation can be worked up by a method known per se. In general the catalyst is de-activated at some point during the processing of the polymer. The de-activation is also effected in a manner known per se, e.g. by means of water or an alcohol. Removal of the catalyst residues can mostly be omitted because the quantity of catalyst in the polymer, in particular the content of halogen and transition metal is very low now owing to the use of the catalyst system according to the invention.
Polymerisation can be effected at atmospheric pressure, but also at an elevated pressure of up to 500 MPa, continuously or discontinuously. If the polymerisation is carried out under pressure the yield of polymer can be increased additionally, resulting in an even lower catalyst residue content. Preferably, the polymerisation is performed at pressures between 0.1 and 25 MPa. Higher pressures, of 100 MPa and upwards, can be applied if the polymerisation is carried out in so-called high-pressure reactors. In such a high-pressure process the catalyst according to the present invention can also be used with good results.
The polymerisation can also be performed in several steps, in series as well as in parallel. If required, the catalyst composition, temperature, hydrogen concentration, pressure, residence time, etc. may be varied from step to step. In this way it is also possible to obtain products with a wide molecular weight distribution.